For long time, soybean has been used as important food in Orient because of high protein content and quality. Recently, many studies have shown incidence rate of degenerative chronic diseases -cancer, atherosclerosis, osteoporosis- is higher in the Western people who consumed more animal foods compared to Asian. It has been known that the reduction of Cancer, cardiovascular disease, and osteoporosis is associated with the diet rich in soybean products. Soybean include many kinds of anti-disease components, such as isoflavone, protein, trypsin inhibitor, phytic acid, and saponin. Isoflavone is similar in structure to estrogen and has estrogenic and anti-estrogenic activity. Genistein, which inhibits protein tyrosine kinase, angiogenisis and DNA topoisomerase, has potent anti-cancer activity. Antioxidant activity of isoflavone prevent the oxidation of LDL-cholesterol, as a result, lower the risks of cardiovascular disease. The estrogenicity of isoflavone similar in structure to ipriflavone of osteoporosis drug has been shown to be quiet beneficial to bone health. Soy protein equivalent in nutrition quality to cow milk protein not only have hypocholesterolemic effect, approved by FDA bat also prevent bone calcium from excreting through kidney. Some scientists are studying anti-cancer function of phytic acid and trypsin inhibitor.